Preform conveyor system provided with means for ejecting badly seized preforms

Abstract

A preform conveyor system ( 10 ), of the type including a number of transport elements ( 18 ) which each have at least one grasping device ( 26 ) for carrying a preform, movable between an upper release position and a lower grasping position, characterized in that each grasping device ( 26 ) is linked in terms of upward and downward axial movement to an associated bracket ( 46 ), and in that the bracket ( 46 ) includes a stud ( 74 ) designed to interact slidingly with a fixed ramp ( 78 ), when the grasping device ( 26 ) is in an intermediate axial position between its upper release position and its lower grasping position, so as to cause the grasping device ( 26 ) to slide axially into its upper release position.

1. A conveyor system ( 10 ) for an installation for the manufacture of thermoplastic containers by blow molding using preforms ( 12 ), of the type comprising a number of transport elements ( 18 ) which each have at least one grasping device ( 26 ) for carrying a preform ( 12 ) so as to convey it, in the vertical position, along a path in the downstream direction, inside the installation, of the type in which each grasping device ( 26 ) can move along a vertical axis (A 2 ) relative to the transport element ( 18 ) carrying it so as, when it is brought from an upper release position to a lower grasping position, to engage axially in the neck ( 14 ) of the preform ( 12 ) to be seized, characterized in that each grasping device ( 26 ) is linked in terms of upward and downward axial movement to an associated bracket ( 46 ) which is mounted so that it can slide axially in one direction (A 3 ) and which bears, at its lower axial end, a cam follower element ( 58 ), the bracket ( 46 ) being stressed axially downward so that the cam follower element ( 58 ) interacts with a surface of a fixed cam ( 66 ) provided to bring the grasping device ( 26 ) from its upper release position to its lower grasping position, in that the bracket ( 46 ) comprises a stud ( 74 ) with a bearing surface ( 76 ) designed to interact slidingly with a fixed ramp ( 78 ) comprising a control surface ( 86 ) which is inclined relative to the vertical and oriented generally upward, when the grasping device ( 26 ) is in an intermediate axial position between its upper release position and its lower grasping position, this intermediate axial position corresponding to an incorrect positioning of the grasping device ( 26 ) in the preform ( 12 ), so that the fixed ramp ( 78 ) brings the stud ( 74 ) upward and causes the grasping device ( 26 ) to slide axially into its upper release position so as to eject the associated preform ( 12 ), and in that the fixed ramp ( 78 ) extends axially at a certain height in such a way that, when the grasping device ( 26 ) is in its lower grasping position, the stud ( 74 ) can travel under the fixed ramp ( 78 ) in a passage ( 100 ) provided for this purpose. 
   
   
     2. The conveyor system ( 10 ) as claimed in  claim 1 , characterized in that it comprises a movable ramp ( 102 ) which can take up:
 an active position in which a control surface ( 106 ) of the movable ramp ( 102 ) is adjacent to the upstream end of the inclined control surface ( 86 ) of the fixed ramp ( 78 ), and in which the control surface ( 106 ) of the movable ramp ( 102 ) closes off the entry to said passage ( 100 ) so as to drive the stud ( 74 ) upward onto the fixed ramp ( 78 ); 
 and a retracted position in which the movable ramp ( 102 ) clears said passage ( 100 ) to allow the stud ( 74 ) to travel under the fixed ramp ( 78 ), 
 
     and in that it comprises an actuator ( 118 ) that causes the movable ramp ( 102 ) to take up the active position when a grasping device ( 26 ) is in an intermediate axial position. 
   
   
     3. The conveyor system ( 10 ) as claimed in  claim 2 , characterized in that the actuator ( 118 ) is controlled by a sensor ( 122 ) which can detect when a grasping device ( 26 ) is in an intermediate axial position. 
   
   
     4. The conveyor system ( 10 ) as claimed in  claim 1 , characterized in that the transport elements ( 18 ) are connected to one another so as to form a chain ( 20 ) that is wound around a transport wheel ( 22 ) mounted rotatably on a vertical axis (A 1 ), in that the transport wheel ( 22 ) comprises a ring ( 40 ) having recesses ( 42 ) each designed to receive a preform ( 12 ) with a collar ( 16 ), carrying each preform ( 12 ) by its collar ( 16 ), in that each recess ( 42 ) is associated with a bracket ( 46 ) that is integral in terms of rotation with the transport wheel ( 22 ) and mounted so as to be able to slide relative to the transport wheel ( 22 ), and in that the fixed ramp ( 78 ) is arranged along the transport wheel ( 22 ), upstream of the point at which the chain ( 20 ) leaves the transport wheel ( 22 ). 
   
   
     5. The conveyor system ( 10 ) as claimed in  claim 4 , characterized in that it comprises a fixed ejection bar ( 124 ) positioned at the same height as a portion of the preform ( 12 ), when the preform ( 12 ) is carried by a recess ( 42 ), and positioned downstream of the point at which the chain ( 20 ) leaves the transport wheel ( 22 ),  50  as to eject the preforms ( 12 ) remaining in the recesses ( 42 ) after the stud ( 74 ) has been driven upward. 
   
   
     6. The conveyor system ( 10 ) as claimed in  claim 5 , characterized in that the inclined control surface ( 86 ) of the fixed ramp ( 78 ) is extended downstream by an intermediate control surface ( 88 ), so as to keep the grasping device ( 26 ) in the release position at least as far as the ejection bar ( 124 ). 
   
   
     7. The conveyor system ( 10 ) as claimed in  claim 4 , characterized in that each grasping device ( 26 ) comprises, at its upper axial end, a cylindrical portion ( 30 ) with two facing radial bearing surfaces ( 32 ,  34 ), in that each bracket ( 46 ) comprises a post ( 48 ) extending in a direction parallel to the axis (A 2 ) of sliding of the associated grasping device ( 26 ), on the side of the axis of rotation (A 1 ) of the transport wheel ( 22 ) relative to the grasping device ( 26 ), and a connecting arm ( 50 ) fixed to the upper axial end portion of the post ( 48 ) and extending radially outward, and in that the connecting arm ( 50 ) comprises, at its radial outer end, a fork ( 52 ) that receives the cylindrical portion ( 30 ) of the associated grasping device ( 26 ) and comprises two radial bearing surfaces ( 54 ,  56 ) designed to interact with the radial bearing surfaces ( 32 ,  34 ) of the cylindrical portion ( 30 ) so as to link the bracket ( 46 ) and grasping device ( 26 ) in terms of axial movement.